手性Salen Mn(Ⅲ)配合物催化NaOCl不对称环氧化苯乙烯反应

手性Salen Mn(Ⅲ)配合物催化NaOCl不对称环氧化苯乙烯反应;不对称环氧化;Salen Mn(Ⅲ)配合物;苯乙烯;NaOCl     

一种新型Eu3+ 和Zn2+ 双金属杂核配合物的结构与发光性质

合成了一种新型双金属杂核配合物Eu(TTA)3Zn(Salen).H2O(Salen=双水杨醛缩乙二胺,TTA=2-噻吩甲酰三氟丙酮),并对其进行了结构和荧光性能表征.配合物的晶体属于三斜晶系,Pī空间群.中心Eu(Ⅲ)离子与六个TTA分子的氧原子和Salen分子的两个酚氧原子配位,形成8配位的扭曲四方反棱柱构型.Zn(Ⅱ)离子与Salen分子中的两个酚氧原子和两个氮原子以及一个水分子配位,形成五配位的扭曲的四方锥构型.配合物Eu(TTA)3Zn(Salen).H2O的发光量子效率(18.0%)较配合物Eu(TTA)3.2H2O(12.5%)发光量子效率有明显提高,说明第二配体Zn(Salen).H2O对中心离子有较强的敏化发光作用.     

磺化Salen金属配合物插层水滑石选择性催化氧化甘油制备二羟基丙酮的研究

制备了一系列含不同金属离子的磺化Salen金属配合物插层水滑石催化剂用于甘油催化氧化制备二羟基丙酮(DHA)。利用X射线粉末衍射(XRD)、傅里叶变换红外光谱(FT-IR)及电感耦合等离子发射光谱(ICP)分析手段对催化剂进行了表征。结果表明,磺化Salen配体插入镁铝水滑石(LDH)层板间,金属离子与磺化Salen配体配合,制备出磺化Salen金属配合物插层的水滑石非均相催化剂。反应结果表明,含Cr³⁺及含Cu²⁺催化剂有利于H₂O₂活化,催化活性较高,含Cu²⁺催化剂利于甘油脱氢,DHA选择性较高。含Cu²⁺催化剂用于甘油催化氧化反应时,在pH值为7、60 ℃条件下反应4 h,甘油转化率为40.3%,DHA选择性达到52.9%。     

手性Salen FeⅢ配合物与咪唑配体轴配反应热力学

手性Salen FeⅢ配合物与咪唑配体轴配反应热力学;手性Salen FeⅢ配合物; 热力学; 圆二色光谱     

Y型分子筛中对称与不对称Co(II)Salen型席夫碱配合物的结构和催化性能

用自由配体法将对称、不对称Co(II)Salen型席夫碱配合物封装于Y型沸石分子筛的超笼中, 并采用FTIR、UV- Vis、热分析和催化技术研究了其空间结构和催化性能. 结果表明, 被封装于分子筛超笼中的Salen型席夫碱配合物, 同样具有未封装配合物的物理化学性能, 也没有影响分子筛的框架结构；在以O2作氧化剂, 催化苯乙烯环氧化反应中表现了非常高的反应活性和稳定性；金属配合物的量子化学密度泛函计算结果揭示了配合物的催化性能与轨道能量密切相关.     

Y型分子筛中对称与不对称Co(II)Salen型席夫碱配合物的结构和催化性能

用自由配体法将对称、不对称Co(II)Salen型席夫碱配合物封装于Y型沸石分子筛的超笼中,并采用FTIR、UV-Vis、热分析和催化技术研究了其空间结构和催化性能.结果表明,被封装于分子筛超笼中的Salen型席夫碱配合物,同样具有未封装配合物的物理化学性能,也没有影响分子筛的框架结构;在以O2作氧化剂,催化苯乙烯环氧化反应中表现了非常高的反应活性和稳定性;金属配合物的量子化学密度泛函计算结果揭示了配合物的催化性能与轨道能量密切相关.     

Schiff碱配合物的研究(Ⅴ)——Fe(Salen)NO3与No2-的反应

Salen是最简单的Schiff碱之一。最近发现,其Fe(Ⅲ)的配合物Fe(Salen)NO_3能与仲胺作用,并很快生成致癌物质亚硝胺。另一方面,一些含Fe_4S_4簇的酶能将NO_2~-催化还原成氨。本文研究了Fe(Salen)NO_3与NO_2~-的作用及其产物的某些性质。 1 实验和结果     

卟啉-二芳基乙烯分子及其金属配合物的合成与光致变色特性

以苯甲醛和吡咯为初始原料,经多步反应合成了5-[2,3-双(2,4,5-三甲基-3-噻吩基)马来酰亚胺-N-苯基]-10,15,20-三苯基卟啉(TPPMA)及其金属锌配合物(ZnTPPMA)与铜配合物(CuTPPMA),通过IR,MS,1H NMR和13C NMR确认了化合物的结构,并利用UV-Vis光谱探讨了化合物的光致变色性能.实验结果表明,无论在聚乙烯醇缩丁醛(PVB)膜还是在溶液中,TPPMA在254 nm紫外光照射下,没有光致变色现象,而在254和650 nm的光照下其金属配合物CuTPPMA和ZnTPPMA在溶液及PVB膜中皆可以发生可逆的光致变色反应.     

Salen Co(Ⅱ)配合物催化苯乙烯环氧化的研究

研究了Salen Co(Ⅱ)配合物催化苯乙烯环氧化的反应.考察了不同取代基水杨醛制备的配体所形成的Co配合物1～4及(S,S)-1,2-二苯基乙二胺与水杨醛形成的Co配合物1(S,S)～3(S,S)的催化氧化性能,其中溴取代的配合物2和2(S,S)是最有效的催化剂.以配合物(2)为催化剂,氧气为氧化剂,考察了反应温度、时间、溶剂等因素对苯乙烯环氧化反应的影响.结果表明,最佳反应条件为苯乙烯10 mmol,配合物(2)0.1%,温度90 ℃,反应时间5 h时,苯乙烯的转化率为97.1%,环氧苯乙烷的选择性为58.9%,苯甲醛与苯甲酸的选择性为36.1%.并对反应机理进行了初步探讨.     

辅酶B_(12)模型化合物的研究(V)RCo(Salen)L配合物Co—C键断裂的动力学

运用光度法研究了RCo(Salen)L配合物在甲醇中热分解反应动力学;测定了Co—C键断裂的速率常数及活化能,得到表观速率常数顺序为i-C3H7>i-C4H9>n-C4H9>n-C3H7>C2H5,活化能顺序为i-C3H7相似文献   

Direct and Post‐Synthesis Incorporation of Chiral Metallosalen Catalysts into Metal–Organic Frameworks for Asymmetric Organic Transformations

Two chiral porous metal–organic frameworks (MOFs) were constructed from [VO(salen)]‐derived dicarboxylate and dipyridine bridging ligands. After oxidation of V^IV to V^V, they were found to be highly effective, recyclable, and reusable heterogeneous catalysts for the asymmetric cyanosilylation of aldehydes with up to 95 % ee. Solvent‐assisted linker exchange (SALE) treatment of the pillared‐layer MOF with [Cr(salen)Cl]‐ or [Al(salen)Cl]‐derived dipyridine ligands led to the formation of mixed‐linker metallosalen‐based frameworks and incorporation of [Cr(salen)] enabled its use as a heterogeneous catalyst in the asymmetric epoxide ring‐opening reaction.     

Enantioselective cyanosilylation of aldehydes catalyzed by Mn(salen) complex/triphenyl phosphine oxide

The activation of chiral Mn(salen) complexes with Ph₃PO has been found to provide a good strategy for the asymmetric cyanosilylation of aldehydes. Aromatic aldehydes have been converted into the corresponding cyanohydrin trimethylsilylether in yields up to 95% and ee up to 67% using 0.25 mol% chiral Mn(salen) complex in combination with 10 mol% of achiral Ph₃PO as additive. Copyright © 2007 John Wiley & Sons, Ltd.     

中孔MCM-41锚合Zr（IV）-salen催化剂制备及用于硫化物氧化制亚砜和Knoevenagel缩合反应

通过NH2-MCM-41与水杨醛反应得到席夫碱配体,然后加入八水氧氯化锆形成络合物,制得Zr(IV)-salen-MCM-41催化剂。采用X射线衍射、N2吸附-脱附、热重、红外光谱、电感耦合等离子体发射光谱和能量散射谱等分析手段对催化剂结构进行了表征。在含有该催化剂的体系中进行了硫化物选择氧化为亚砜以及醛与丙二腈和氰乙酸乙酯的Knoveonagel缩合反应,并考察了催化剂的循环使用性能。     

Catalytic Asymmetric Synthesis of O‐Acetylcyanohydrins from Potassium Cyanide,Acetic Anhydride,and Aldehydes,Promoted by Chiral Salen Complexes of Titanium(IV) and Vanadium(V)

The utility of the chiral [Ti(μ‐O)(salen)]₂ complexes (R)‐ and (S)‐ 1 (H₂salen was prepared from (R,R)‐ or (S,S)‐cyclohexane‐1,2‐diamine and 3,5‐di(tert‐butyl)‐2‐hydroxybenzaldehyde) as catalysts for the asymmetric addition of KCN and Ac₂O to aldehydes to produce O‐acetylcyanohydrins was investigated. It was shown that the complexes were active at a substrate/catalyst ratio of 100 : 1 and produced the O‐protected cyanohydrins with ee in the range of 60–92% at −40°. Other complexes, [Ti₂(AcO)₂(μ‐O)(salen)₂] ((R)‐ 4 ) and [Ti(CF₃COO)₂(salen)] ((R)‐ 5 ), were prepared from (R)‐ 1 by treatment with different amounts of Ac₂O and (CF₃CO)₂O, and their catalytic activities were tested under the same conditions. The efficiency of (R)‐ 4 was found to be even greater than that of (R)‐ 1 , whereas (R)‐ 5 was inactive. The synthesis of the corresponding salen complexes of V^IV and V^V, [V(O)(salen)] ((R)‐ 2 ) and [V(O)(salen)(H₂O)] [S(O)₃OEt] ((R)‐ 3 ), was elaborated, and their X‐ray crystal structures were determined. The efficiency of (R)‐ 3 was sufficient to produce O‐acetyl derivatives of aromatic cyanohydrins with ee in the range of 80–91% at −40°.     

Investigation of Lewis Acid versus Lewis Base Catalysis in Asymmetric Cyanohydrin Synthesis

The asymmetric addition of trimethylsilyl cyanide to aldehydes can be catalysed by Lewis acids and/or Lewis bases, which activate the aldehyde and trimethylsilyl cyanide, respectively. It is not always apparent from the structure of the catalyst whether Lewis acid or Lewis base catalysis predominates. To investigate this in the context of using salen complexes of titanium, vanadium and aluminium as catalysts, a Hammett analysis of asymmetric cyanohydrin synthesis was undertaken. When Lewis acid catalysis is dominant, a significantly positive reaction constant is observed, whereas reactions dominated by Lewis base catalysis give much smaller reaction constants. [{Ti(salen)O}₂] was found to show the highest degree of Lewis acid catalysis, whereas two [VO(salen)X] (X=EtOSO₃ or NCS) complexes both displayed lower degrees of Lewis acid catalysis. In the case of reactions catalysed by [{Al(salen)}₂O] and triphenylphosphine oxide, a non‐linear Hammett plot was observed, which is indicative of a change in mechanism with increasing Lewis base catalysis as the carbonyl compound becomes more electron‐deficient. These results suggested that the aluminium complex/triphenylphosphine oxide catalyst system should also catalyse the asymmetric addition of trimethylsilyl cyanide to ketones and this was found to be the case.     

Vanadyl salen complexes covalently anchored to an imidazolium ion as catalysts for the cyanosilylation of aldehydes in ionic liquids

Two vanadyl salen complexes having peripheral styryl substituents have been reacted with 1-methyl-3-(3-mercaptopropyl)-imidazolium chloride using azoisobutyronitrile as radical initiator. The resulting compounds contain at the same time a vanadyl salen complex and one imidazolium cation. In agreement with the expectations in view of their structure, these compounds were insoluble in conventional organic solvents, but completely miscible in imidazolium ionic liquids. These vanadyl salen complexes bonded to an imidazolium cation are highly active and reusable catalysts for the cyanosilylation of aldehydes. Moderate enantiomeric excesses were obtained using the chiral version of this complex.     

The First Catalytic Enantioselective Nozaki-Hiyama Reaction

The Nozaki-Hiyama reaction can be performed in an enantioselective catalytic way! The catalytic system utilizes 10 mol % of an inexpensive chiral [Cr(salen)] complex. The [Cr(salen)]/Mn/Me(3)SiCl system effectively promotes the enantioselective addition of allyl chloride to aliphatic and aromatic aldehydes at room temperature (65-89 % ee, 40-60 % yield).     

Enantioselective Heterogeneous Epoxidation and Hetero‐Diels‐Alder Reaction with Mn‐ and Cr‐salen Complexes Immobilized on Silica Gel by Radical Grafting

Vinyl‐substituted chiral salens (salen=bis(salicylidene)ethylidenediamine) are used for attachment to Me₃Si‐hydrophobized silica gel (controlled‐pore glass, CPG), carrying covalently bound mercaptopropyl ‘substituents', by AIBN‐mediated radical addition of SH groups to styryl C=C bonds (Scheme 1, Table 1, and Figs. 1 and 2). The immobilized Mn‐ and Cr‐salen complexes, thus accessible, have been employed in enantioselective epoxidations (Scheme 2, Tables 2 and 3, and Fig. 3) and hetero‐Diels‐Alder additions of aldehydes to Danishefsky's diene (Scheme 3, Tables 4 and 5, and Figs. 4 and 5), with an emphasis on multiple use of the immobilized catalysts. The enantioselectivities (es) of the two reactions were very similar to those reported for homogeneous conditions. After five to seven runs, all the CPG‐bound Mn‐salen complexes performed somewhat less well (70 instead of 75% es with styrene; Fig. 3). The Cr complex, which was shown to give rise to a linear relationship between the enantiomeric purities of ligand and product under homogeneous conditions (Fig. 4), exhibited the opposite behavior: after five runs, the enantioselecitivity of the hetero‐Diels‐Alder reaction had risen (from an average of 76 to ca. 83%) to remain constant for another five runs (Fig. 5). We have established for both catalysts that no reaction takes place in the supernatant solution (no leaching of catalytically active Mn or Cr species from the CPG into solution; heterogeneity test; Tables 3 and 5). The results described are yet another demonstration for the successful ‘conversion' of homogeneous to heterogeneous catalysts by immobilization on hydrophobic CPG, with multiple application of the same catalyst batch.     

Electrochemical Modified Electrodes Based on Metal‐Salen Complexes

Abstract

A general view of the electroanalytical applications of metal‐salen complexes is discussed in this review. The family of Schiff bases derived from ethylenediamine and ortho‐phenolic aldehydes (N,N′‐ethylenebis(salicylideneiminato)—salen) and their complexes of various transition metals, such as Al, Ce, Co, Cu, Cr, Fe, Ga, Hg, Mn, Mo, Ni, and V have been used in many fields of chemical research for a wide range of applications such as catalysts for the oxygenation of organic molecules, epoxidation of alkenes, oxidation of hydrocarbons and many other catalyzed reactions; as electrocatalyst for novel sensors development; and mimicking the catalytic functions of enzymes. A brief history of the synthesis and reactivity of metal‐salen complexes will be presented. The potentialities and possibilities of metal‐Salen complexes modified electrodes in the development of electrochemical sensors as well as other types of sensors, their construction and methods of fabrication, and the potential application of these modified electrodes will be illustrated and discussed.     

Chiral salen-aluminum complex as a catalyst for enantioselective alpha-addition of isocyanides to aldehydes: asymmetric synthesis of 2-(1-hydroxyalkyl)-5-aminooxazoles

In the presence of a catalytic amount of (salen)Al(III)Cl complex (4e), reaction between alpha-isocyanoacetamides (1) and aldehydes (2) afforded the corresponding 5-aminooxazoles (3) in good yields and enantioselectivity.